Orlando police officers seen outside of Pulse nightclub after a fatal shooting and hostage situation where 50 people died on June 12, 2016 in Orlando, Florida. Gerardo Mora/Getty Images ORLANDO, Fla. (Reuters) - U.S. authorities investigated on Monday whether anyone helped the gunman who massacred 49 people at a gay nightclub in Orlando, but said they did not believe anyone connected to the shooting posed a current danger to the public.

The FBI and other agencies were looking at evidence inside and in the closed-off streets around the Pulse nightclub, where a shooter pledging allegiance to Islamic State carried out the deadliest mass shooting in U.S. history, and the worst attack on U.S. soil since Sept. 11, 2001.

The gunman, Omar Mateen, a New York-born Florida resident and U.S. citizen who was the son of Afghan immigrants, was shot and killed by police who stormed the club early Sunday morning with armored cars after a three-hour siege.

Officials said on Sunday the death toll was 50. On Monday they clarified that this included Mateen.

By Monday morning, all but one of those killed had been identified and about half the families of the dead had been notified, officials said.

Julissa Leal, 18, and her mother drove down to the Florida city from Lafayette, Louisiana in search of her brother, 27-year-old Frank Hernandez. They knew he was at the club with his boyfriend, who lost him in the chaos.

"We haven't heard anything, don't know anything," Leal said said, fighting back tears. "I'm going to see him again. I'm going to see him again."

A photo of Omar Mateen taken from his MySpace page. Screenshot/MySpace

Law enforcement officials were looking for clues as to whether anyone worked with Mateen on the attack, said Lee Bentley, U.S. Attorney for Florida's middle district.

"There is an investigation of other persons, we are working as diligently as we can on that," Bentley told a news conference. "If anyone else was involved in this crime, they will be prosecuted."

Officials stressed they believed there had been no other attackers and that they had no evidence of a threat to the public.

Mateen, 29, called emergency services during the shooting and pledged allegiance to the leader of the militant Islamic State group, officials said. His father said on Sunday his son was not radicalized, but indicated Mateen had strong anti-gay feelings. His ex-wife described him as mentally unstable and violent toward her.

Islamic State reiterated on Monday a claim of responsibility. "One of the Caliphate's soldiers in America carried out a security invasion where he was able to enter a crusader gathering at a nightclub for homosexuals in Orlando," the group said in a broadcast on its Albayan Radio

Although the group claimed responsibility, this did not necessarily mean it directed the attack: there was nothing in the claim indicating coordination before the rampage between the gunman and Islamic State.

The attack, denounced by President Barack Obama as an act of terror and hate, reignited the debate over how best to confront violent Islamist militancy, and immediately became a sharp point of disagreement in the campaign for the Nov. 8 presidential election.

Friends and family members embrace outside the Orlando Police Headquarters during the investigation of a shooting at the Pulse night club in Orlando, Florida Thomson Reuters Democratic candidate Hillary Clinton, speaking on MSNBC, said the United States should walk a fine line in bolstering security without demonizing Muslims, and also called for tougher gun safety measures. Trump, in CNN and Fox News interviews, criticized the U.S. Muslim population for not reporting suspicions to authorities, and reiterated his call for a temporary ban on Muslims entering the country.

The rampage began just after 2 a.m. on Sunday at the nightclub in the heart of Orlando, about 15 miles (25 km) northeast of the Walt Disney World Resort. Orlando is one of the most popular tourist destinations in the United States, drawing some 62 million visitors a year.

Some 350 patrons were attending a Latin music event at the club and survivors described scenes of carnage and pandemonium as the shooter took hostages inside a bathroom.

Police said on Monday that the officers who responded to the attack saved "dozens" of clubgoers and eventually used explosives and a heavy vehicle to punch a hole in the building's wall through which more people escaped. Mateen also emerged through the hole and was shot dead, police said.

Father 'would have arrested' son

Mateen was an armed guard at a gated retirement community, and had worked for the global security firm G4S for nine years. He had cleared two company background screenings, the latest in 2013, according to G4S..

Despite his 911 call expressing support for Islamic State, U.S. officials said on Sunday they had no conclusive evidence of any direct connection with foreign extremists.

"So far as we know at this time, his first direct contact was a pledge of bayat (loyalty) he made during the massacre," said a U.S. counterterrorism official. "This guy appears to have been pretty screwed up without any help from anybody."

Mateen's father, Seddique Mir Mateen, told reporters on Monday that he was angered by his son's actions.

"I am sorry," the father said. "If I did know, 1 percent, that he was committing such a crime myself, I would have arrested him myself, I would have called FBI."

FBI assistant special agent in charge Ron Hopper (C), law enforcement and local community leaders speak during a press conference June 12, 2016 in Orlando, Florida. 50 people are reported dead and 53 were injured at a mass shooting at the Pulse nightclub in what is now the worst mass shooting in U.S. history. Gerardo Mora/Getty Images In an earlier interview with NBC news, the father described an incident in downtown Miami in which his son, saw two men kissing in front of his wife and child and became very angry.

Mateen's former wife, Sitora Yusufiy, told reporters near Boulder, Colorado, that she had been beaten by Mateen during outbursts of temper in which he would "express hatred towards everything".

Outside the Port Saint Lucie gym where Mateen once worked as a security guard, member Jon Mckenzie on Monday recalled Mateen as being rude about insisting on seeing identification.

"He basically told me have your (driver's) license or I won't let you in regardless of whether you live here or not," Mckenzie said. He never reported it. "I figured everyone has a bad day."

Authorities said on Sunday that Mateen had been twice questioned by FBI agents in 2013 and 2014 after making comments to co-workers about supporting militant groups, but neither interview led to evidence of criminal activity.

Homegrown attacks

The attacks underlined the inherent difficulties of providing security at open public events.

"We are determined to continue living in an open and tolerant way even if such murderous attacks plunge us into deep mourning," said German Chancellor Angela Merkel, during a visit to China, as messages of condolence poured in from around the world.

The attack came six months after a married couple in California - a U.S.-born son of Pakistani immigrants and a Pakistani-born woman he married in Saudi Arabia - killed 14 people in San Bernardino at an office holiday party in an shooting rampage inspired by Islamic State. The couple died in a shootout with police hours after that attack.

The most deadly attack on U.S. soil inspired by violent Islamist militancy was on Sept. 11, 2001, when al Qaeda-trained hijackers crashed jetliners into New York's World Trade Center, the Pentagon and a field in Pennsylvania, killing some 3,000 people.

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